Page 972 - College Physics For AP Courses

960 Chapter 21 | Circuits, Bioelectricity, and DC Instruments
Glossary
ammeter: an instrument that measures current
analog meter: a measuring instrument that gives a readout in the form of a needle movement over a marked gauge
bridge device: a device that forms a bridge between two branches of a circuit; some bridge devices are used to make null measurements in circuits
capacitance: the maximum amount of electric potential energy that can be stored (or separated) for a given electric potential capacitor: an electrical component used to store energy by separating electric charge on two opposing plates
conservation laws: require that energy and charge be conserved in a system
current: the flow of charge through an electric circuit past a given point of measurement
current sensitivity: the maximum current that a galvanometer can read
digital meter: a measuring instrument that gives a readout in a digital form
electromotive force (emf): the potential difference of a source of electricity when no current is flowing; measured in volts
full-scale deflection: the maximum deflection of a galvanometer needle, also known as current sensitivity; a galvanometer with a full-scale deflection of has a maximum deflection of its needle when flows through it
galvanometer: an analog measuring device, denoted by G, that measures current flow using a needle deflection caused by a magnetic field force acting upon a current-carrying wire
internal resistance: the amount of resistance within the voltage source
Joule’s law: the relationship between potential electrical power, voltage, and resistance in an electrical circuit, given by:

junction rule: Kirchhoff’s first rule, which applies the conservation of charge to a junction; current is the flow of charge; thus,
whatever charge flows into the junction must flow out; the rule can be stated
Kirchhoff’s rules: a set of two rules, based on conservation of charge and energy, governing current and changes in potential
in an electric circuit
loop rule: Kirchhoff’s second rule, which states that in a closed loop, whatever energy is supplied by emf must be transferred into other forms by devices in the loop, since there are no other ways in which energy can be transferred into or out of the circuit. Thus, the emf equals the sum of the (voltage) drops in the loop and can be stated:

null measurements: methods of measuring current and voltage more accurately by balancing the circuit so that no current
flows through the measurement device
ohmmeter: an instrument that applies a voltage to a resistance, measures the current, calculates the resistance using Ohm’s law, and provides a readout of this calculated resistance
Ohm’s law: the relationship between current, voltage, and resistance within an electrical circuit:
parallel: the wiring of resistors or other components in an electrical circuit such that each component receives an equal
voltage from the power source; often pictured in a ladder-shaped diagram, with each component on a rung of the ladder potential difference: the difference in electric potential between two points in an electric circuit, measured in volts potentiometer: a null measurement device for measuring potentials (voltages)
RC circuit: a circuit that contains both a resistor and a capacitor
resistance: causing a loss of electrical power in a circuit
resistor: a component that provides resistance to the current flowing through an electrical circuit
series: a sequence of resistors or other components wired into a circuit one after the other
shunt resistance: a small resistance placed in parallel with a galvanometer G to produce an ammeter; the larger the current to be measured, the smaller must be; most of the current flowing through the meter is shunted through to
This OpenStax book is available for free at http://cnx.org/content/col11844/1.14